Fix boolean Option missing type and default in --help output (Fixes #493)

[sayantancodex]

Fixes #493

Summary

Boolean typer.Option fields were not displaying their type and default value in the CLI help output when using Rich formatting.

Changes

• Removed logic that prevented displaying False as a default value for boolean options (typer/core.py)
• Enabled display of boolean metavar in help output (typer/rich_utils.py)
• Represented boolean type as BOOL for concise formatting

Testing

• All existing tests pass (1157 passed, 0 failed)
• Added regression test: tests/test_issue_493.py
• Verified manually via CLI output

Example

Before:
--debug Enable debug mode

After:
--debug BOOL Enable debug mode [default: False]

[sayantancodex]

This PR fixes a bug in CLI help formatting (Issue #493).

Could a maintainer please add the appropriate label (e.g., bug) so CI checks can pass?

[svlandeg]

I added a label, but that was not the only issue. I'll put this PR in draft, feel free to mark is as "ready for review" once the CI is green.